In order to characterize the response to painful stimuli in the newborn and provide data necessary to develop pain-intervention strategies in the newborn, behavioral state, cry and heart rate respiratory, blood pressure and oxygenation patterns will be measured in premature and full term infants during non-painful handling procedures and medically-indicated painful procedures (heel stick). 187 subjects will be studied weekly until they are discharged or reach term (40 weeks gestational age).